1. Field of the Invention
The present invention relates to an IC mounting/demounting system for transferring an IC on a tray and mounting the IC on an IC socket on a socket board for a burn-in process or demounting the IC from the IC socket and transferring the IC on the tray.
2. Description of the Related Art
Conventionally, a fabricated IC (IC package) passes through a burn-in process turned on for a predetermined time at a high temperature of, for example, 120 to 130.degree. C. and thereafter, undergoes an electrical operation test.
In the burn-in process, an IC is mounted on each of a plurality of IC sockets arranged on a socket board, that is, the IC is electrically connected with the IC socket, and the socket board is set in a burn-in oven. Therefore, a process for transferring an IC to an IC socket on a socket board and mounting/demounting the IC on or from the IC socket is necessary before and after the burn-in process and an IC mounting/demounting system is used for the process.
FIG. 27 is a perspective view showing an example of a conventional IC mounting/demounting system. In the figure, a socket board (burn-in board) 1 on which a plurality of IC sockets (not illustrated) are mounted is transferred one by one from a board magazine 3 by a board transfer section 2. A tray housing section 5 in which a plurality of trays 4 are housed is set nearby the board transfer section 2. A plurality of IC's (not illustrated) are mounted on each tray 4.
The IC's are transferred between the socket board 1 and the tray 4 by a robot body 6. Two mounting/demounting heads 7 for sucking and holding the IC's are mounted on the robot body 6. The interval between these two mounting/demounting heads 7 can be adjusted in accordance with the pitch between the IC sockets on the socket board 1 and the pitch between the IC's housed in the tray 4. Moreover, a tray chuck 8 for transferring the tray 4 is mounted on the robot body 6.
Next, the operation will now be described. For example, to mount the IC's on the tray 4 housed in the tray housing section 5 on the IC sockets on the socket board 1, the mounting/demounting heads 7 are moved onto the IC on the tray 4 by the robot body 6 to suck and hold two IC's. Thereafter, the mounting/demounting heads 7 are moved over the IC sockets on the socket board 1 to mount the IC on the IC sockets and cancel the suction.
In this case, because the IC socket is provided with a cover for opening/closing the contacts, the IC is set to the IC socket by pressing the cover with the mounting/demounting head and thereby opening the contacts. Then, by moving the mounting/demounting head 7 upward, the pressure on the cover is released, the contacts are closed, and the IC is held by the IC socket. Moreover, the IC is positioned in the mounting/demounting head 7 by correcting the shoulder portions of the IC by chucks (not illustrated) from four directions.
Thus, the IC's are mounted by two on the IC sockets on the socket board 1 from the tray 4. When an IC is mounted on every IC socket on the socket board 1, the next socket board 1 is supplied by the board transfer section 2. When all the IC's are removed from the tray 4, a new tray 4 is supplied by the tray chucking section 8.
As described above, a burn-in process is carried out after the socket board with the IC's mounted on the IC sockets is placed in a burn-in oven (not illustrated). After the burn-in process, the IC's on the IC sockets are transferred to the tray 4 by reversing the above procedure.
In the conventional IC mounting/demounting system constructed as described above, it is necessary to position the IC by the chucks and press the cover of the IC socket by socket pushers (not illustrated) of the mounting/demounting head when the IC is mounted and demounted on the IC socket. However, because various sizes of IC sockets are used corresponding to the IC to be mounted, it is necessary to store various mounting/demounting heads having a socket pusher corresponding to each IC socket size and the chucks corresponding to the IC size and to replace the whole of the mounting/demounting head whenever the type of IC and IC socket are changed. To perform the above mounting/demounting head replacement, operations of the system must be stopped for 15 to 20 minutes or more thereby lowering operation efficiency. Particularly, as the number of diversified low-volume products increases, the frequency of mounting/demounting head replacement increases and the time and labor required for the replacement greatly influence operation efficiency.
There is a system for simultaneously transferring a lot of IC's by a robot having a plurality of mounting/demounting heads corresponding to only IC's and IC sockets of specific sizes. However, the system is also unsuitable for the above diversified low-volume product manufacture because the whole system must be stopped while the different size IC's and IC sockets are handled.